Method of treating blast-furnace slag.



T Tfw. WOOD. METHOD OF TREATING BLAST FURNACE SLAG.

PATENTED APR. -7, 1908.

m. bssnvo.

PPLI TIOH FILED H A 0v 1905 2 SHEETS-SHEET 1.

A Q 3 3 Q m 1 .No. 883,770. PATENTED APR. 7, 1908 F. W.-WOOD.

METHGD OP TREATING BLAST FURNACE SLAG.

' APPLIOATION FILED NOV.8,1905.

2 snsms-snsm 2 a t minke? Wa d,

a 0mm FREDERICK WILLIAM WOOD,

OF BALTIMORE, MARYLAND.

METHOD OF TREATING BLAST-FURNACE SLAG.

Specification of Letters Patent.

Patented. April '7, 1908.

Application filed. November 8, 1906. Serial No. 286,347.

To all whom it may concern:

Be it known that I, FREDERICK WILL 1AM WOOD, of Baltimore, State of Maryland, have invented a new and useful Improvement in Methods of Treating Blast-Furnace Slag, of which the following is a specification.

I Ordinarily the disposal .of blast furnace slag is attended by considerable expense, to

- offset which efforts have been made to utilize it as a material for road-ballast, roofing material, and in the manufacture of cement. For each of these pur oses it is necessary that the slag shall be su -divided to a greater or'less extent. The usual method of pre aration for cement making is to bring t e molten slag from the'furnace into contact with a large volume of water, the result being the formation of a cellular, vitreous mass,

which after being dried is ground to a fine powder. During this treatment the slag takes up a large percenta e of water, frequently as high as twentyve er cent, demanding the consumption of a arge amount of fuel in order to dry it thoroughly, as is necessary preparatory to use. The molecular condition of the slag, resulting from the sudi den chill in the water, is not that best suited prolonging the cooling action.

. carefully avoided.

for the production of high gradecement.

The aim of my invention is to avoid the expense attending the ordinary procedure, and at the same time convert the material to a eculiar crystalline condition better adapted or the manufacture of cement and for other uses,a vitreous or inert condition being lin action is continued as the material slow y changes condition until it finall assumes the form of hard separate no ules. The sub-division is effected by repeated con tact of molten slag with portions previously chilled by contact with the cold surface. The

stalline state essential to action produces a flowing, tumbling, pasty mass, which, as the coolin progresses, separates into nodules, whic are prevented from clingin together, as they would otherwise do, byt eir constant change of position. In order to effect the tumbling action and the progressive movement of the material toward the point of delivery, as the change of condition progresses, I may employ any suitable ap garatus, preferably an inclined rotary tube'or arrel or circular or polygonal section, into and through which the material is caused to flow from one end to the other. The rotary motion of the sup orting surface in a direction transverse to t e flow of the material thereover, results in a constant agita tionand a tumbling motionof the material, which is repeatedly lifted and caused to fall back upon the moving mass below while advancing slowly toward thepoint of dischar e. The operation may be continuous, but 516 change in the character of the material is rogressive and may be controlled and proonged by changing the inclination and the speed of rotation of the tube or barrel.

The prolongation of the cooling period, or the eriod consumed in changing the material portance. with advantage to several minutes. graduall or progressively cooled, the material w' l assume a vitreous or inert condition.

In carrying out my method, the slag remains in contact with the coolin surface for an instant only at a time, and t e thin skin thereby formed on the nodule is brought back toward the molten or pasty condition again by contact with the more hi hly heated portions of the mass. Thus su den solidification is prevented, while at the same time the agitation of the mass prevents the nodules from cohering. The operation is facilitated by subjecting the material, during the above action, to an artificial cooling influence. This may be effected by flowing cold water or other cooling fluid around the exterior of the cylinder, the effect .being not only to reduce the temperature of the contained air but also the temperature of the surface on which the material rests, and with which the particles are brou ht successively in'contact as the stream ows toward the delivery end. As the slag passes from a pasty to a solid state, is of im- In practice, it may be extended Unlesscut is sulii from the liquid to a pasty condition and thence to the solid state, the constant agitation insures its separation into small pieces or nodules, the size being governed by the rate of rotation and the rate of cooling. By the gradual cooling a molecular condition is obtained referable for cement making purposes to tile vitreous condition producer by sudden cooling. Moreover, theslag 1s obtained in a form in which it can be used without subsequent treatment other than separating the sizes suitable for the purpose desired.

In some cases it is advanta eous to subject the mass while cooling to t e action of a strong current of air. This may be accomplished by any suitable means, such for ex ample as a 'et acting at elther end of the cylinder to induce currents of air therethrough. In such case the cooling is accomplished, first, by contact with the cold supporting surface of the chamber; second, by radiation to the cold walls around and above the mass,

and, third, by the cooling current above mentioned.

The slag as it leaves the blast furnace contains from one and one-half per cent. of sulfur to three er'cent.; the combination presof calcium. The presence of this com ound in cement is highly objectionable From the fact that it is slowly oxidized to sulfate of calcium by the action of atmospheric air, the chan e being accompaniec by an increase of volume, which dismtegrates the mortar or concrete. By exosure of the highly heated slag, as hereinbefore described, to the oxidizing influence of the passing air, a considerable portion of the sulfurous contents is oxidized, partly to sulfurous anhydrid, which passes away as a gas, and partly with the formation of sulfate of calcium, the presence of which in cement is not objectionable.

The accompanying drawings illustrate an apparatus sultable for carrying out my invention.

Figure 1 is a side elevation, of a rotary cylinder and attendant parts suitable for carrying out my method. Fig. 2 is a longitudinal vertical section of the same on the line 22, Fig. 3. Fig. 3 is an end elevation of the cylinder and the parts for supporting and turn ing the same.

Referring to the drawings A represents an inclined tubular body, which may have a circular section as shown or a polygonal section having its inner surface smooth or roughened as may be referred. This cylinder is supported on beneath it and circumferentially grooved.

Motion may be communicated from any suitable source and through any suitable mechanism. I recommend, as shown, an electric motor, 0, from which motion is communicated through an intermediate gear, D,

ed rollers, B, lying source of supply for showerin cold water on the outside of the cylinder w ien required.

G is a stationary pipe located in the lower end of the cylinder and perforated for the purpose of dehvering jets toward the receiv- 1ng end of the same. This pipe may be connected with a fan or other source of cold air supply, or with a source of high pressure steam supply, in order that the dry steam issuing therefrom may induce a flow of air longitudinally through the cylinder and over the surface of the material flowing downward therein.

H is a chute through which the molten slag is delivered into the upper end ,of the cylinder. I

I is a conductor through which the nodules are delivered from the cylinder.

The apparatus constitutes no part of th present invention, and may be modified at will or replaced by any other form of apparatus which will subject the slag to the influences above described.

Having described my invention, what I claim is:

1. The method of treating blast furnace slag consisting in subjecting the same to continuing agitation during its gradual change from a fluid to a solid state.

2. The method of treating blast furnace slag consisting in subjecting the same to agitation of the pasty nodules in contact with one another and to a progressive movement during its change from a fluid to a solid state.

'3. The method of treating molten blast furnace slag consisting in delivering the same upon a cooling surface and tumbling the resulting asty nodules over and over in contact with one another until they assume a solid condition.

4. The method of converting molten slag into solid nodules, consisting in flowing the.

material forward over a cooling surface and at the same time tumbling the mass over and over in a direction transverse to the flowing movement, to cause repeated contact of the nodules while changing from a pasty to a solid state.

5. The method of treating molten furnace slag consisting in flowing the same gradually downward over an inclined cooling surface, and at the same time lifting the surface transversely to the line of flow; whereby the advancing nodules are caused to repeat edly tumble back upon one another while passing from a fluid to a solid state.

6. The method of treating molten blast furnace slag consisting in EflowingQthe'Zsame 5 over a ii'ovingsurfaee subject to the influover an artificially cooled mo surface In testimony whereof I hereunto set my while passing from a. fluid to a solis state. hand this first day of November, 1905, in the 7. The method of treating molten blast presence of two attesting witnesses. furnace slg g consisting in flowing the same W FREDERICK WILLIAM W001).

1tnesses:

T1105. KELL Bnmronn, A G. W. Bnmmnn.

ence of a cooling current while paaing from a fluid to a solid state; 

